Unity SMDI heartbeat message

Answered Question
Apr 29th, 2010

I have a dual Unity SMDI integration with a Centrex phone system and the phone company is asking us to change the SMDI link heartbeat message number.  Right now they saying we sending 9999999999 but I can't find that anywhere in the Switch Configuration Editor.  Does anyone know where to find this?  Thanks.


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Correct Answer by David Hailey about 6 years 5 months ago

Flip thru this link: http://www.ciscosysteme.org/en/US/docs/voice_ip_comm/unity/5x/integration/voice_card/guide/cxsecu5x.html

Down towards the bottom you'll come across the prefix info for SMDI and where it is set.


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mdaswani Thu, 04/29/2010 - 08:29

I do have the prefixes set for our number ranges but what relation is that to the heartbeat?  My extension length is 5 and SMDI legth is 10.  The prefixes are 31220, 31266, 31269 and 31292

David Hailey Thu, 04/29/2010 - 08:38

I would check with the Telco provider and ask them where they are seeing this 9999999999 extension. Out of curiousity, what are your DN's for MWI On and Off? I have read (long time ago) that some voice systems would send a essentially a false MWI message as what was considered the MWI heartbeat.


mdaswani Thu, 04/29/2010 - 08:43

The MWI On and Off are left blank in the Edit Switch Configuration utility

David Hailey Thu, 04/29/2010 - 08:57

OK, that's correct.  It may have sounded odd to ask (and I assume this has been working fine); however, I wanted to rule out some mishap caused by a misconfiguration of some sort.

As far as the set up --> Can you lay that out for me.  Unity --> Modem --> Centrex?  What is the connection path?  I don't know of or see anything where Unity would actually be sending this but it's obviously coming from somewhere.  So, let's go from there and see if we can get this pinned down.


mdaswani Thu, 04/29/2010 - 09:23

The SMDI design is as follows...we also have the analog lines split off to both Unity servers as is discussed in the integration guide

Primary Unity ---EIA-232---- SMDI Modem-----PL------ Centrex



            A/B switch (for redundancy)



Failover Unity ---EIA-232---- SMDI Modem------PL------ Centrex

David Hailey Thu, 04/29/2010 - 10:50

It's been a while for me in terms of an SMDI integration to Centrex. The modem is essentially the facilitator in the conversation. Let me take a look and see what's out there explaining the full functionality of the modem. My thought is that, like I said - I don't know where you would set up an SMDI heartbeat DN or code within Unity - it's not even discussed in the various integration guides I've seen on the topic (unless I'm missing something) - so possibly the modem has something to do with what the provider is receiving. May or may not be off-base but worth looking at.

rob.huffman Thu, 04/29/2010 - 11:26

Hi Manish,

Just to add a little to the great tips from Hailey (+5 Hailey ...I really

like the way you troubleshoot this stuff!)

Under the CMI parameters - look for;

Some voice mail systems can send a fake OP:MWI message which is used as an SMDI link "heart-beat" message (for example OP:MWI 5551212). The voice mail system expects a negative acknowledgment (NAK) response from the far end as a means to determine if the SMDI link functions correctly. The parameter KeepAliveDn should contain the agreed upon fake station number for this activity.





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David Hailey Thu, 04/29/2010 - 11:30

There you go, Rob. +5 to you on that. That's exactly what I was referring to but it's been a long time since I've read that so I didn't recall the full details. Excellent.

mdaswani Thu, 04/29/2010 - 11:31

Thanks Rob..but switch is Centrex, not CM...so I can't change any of those parameters

David Hailey Thu, 04/29/2010 - 11:43

True, the guide is for CM - but there may be something similar going on here. The only place I can see that occurring if it is traffic TO the Centrex provider is at the modem itself.

rob.huffman Thu, 04/29/2010 - 11:40

Hi Manish,

Duh! Sorry about that buddy. It doesn't seem to come from Unity

anywhere that I can see.



mdaswani Fri, 04/30/2010 - 06:23

I heard from the telco and you are correct.  This a fake MWI message they are seeing as OP:MWI 9999999999!. (However, at first glance on the integration monitor I don't see these MWI messages going through)

The question is now where to change it?  Under the Edit Switch Utility my integration is Centrex and under the MWI tab it is set to 'MWI Default' and Active is checked.  The On and Off boxes are left blank.  Unfortunately, there doesn't seem to be a help section for the Edit Switch Utility parameters.

Should it be changed there?  Or should I create a dummy mailbox and put a message in there to initiate the MWI?

I have attached a screen shot of the MWI tab..


William Bell Fri, 04/30/2010 - 06:48

I took a look at this and I was trying to get the params for the switch.ini to see if there was some param that would generate this keepalive. I have done the keepalive from VG-248 and I have seen the configs on PIMG. So, this means that there is a possibility that the SMDI switch you have in your diagram is generating this message. Can you console into that switch? Based on the diag I am assuming you have dialogic cards installed directly in your unity and using some SMDI/modem like device to send the SMDI on a 0B+D (that is what Verizon centrex uses anyway).

Anyway, it is possible that the SMDI/modem is sending this.

I assume one could verify this by jacking a laptop console into the Unity console port to see if it is streaming out the open MWI message (that is what OP:MWI means). Thought this would be intrusive (slightly).

So, I would check to see if the SMDI modem is inserting this and then use your laptop to check data that is fed out of the Unity console port.




David Hailey Fri, 04/30/2010 - 07:27

I agree with Bill - this is what I was getting at earlier. I don't know where you would have control over this in Unity so I am leaning towards the Modem as the source...but I don't know if you control this or the Telco. Like I said, been a long time on the Centrex integrations...

mdaswani Wed, 05/05/2010 - 13:35

Here's an update on this issue:

I captured a SMDI log for the evening and did in fact notice a MWI request for 9999999999.  There were about 12 of these lasting for about 30 minutes.  I don't have a subscriber configured for this extension though so I don't know where this is coming from...

OP:MWI 9999999999!, 01:06:25,  , Outgoing, Lamp ON for Extension
MWI9999999999 INV, 01:06:28,  , Incoming, INVALID PACKET

William Bell Wed, 05/05/2010 - 14:43

You captured the lot from what system? Did you see messages from unity or your smdi modem?

mdaswani Wed, 05/05/2010 - 14:52

From Unity...I ran the Integration Monitor in tools depot and logged the output.  These have to be from the Unity as that's what the log output indicates.  You see Unity sending a MWI Lamp On message for 9999999999 and then receiving an response that it's Invalid.  Correct?


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